It is well known that when citrus fruit is processed to produce juices for packaging, canning, or concentration, citrus waste residue remains. This residue is useful in that it contains oils, fermentable substances and nutritional material useful as an animal feed.
Citrus molasses is made from the citrus waste residue by treating the residue with lime to facilitate the release of bound juices. The citrus waste residue is then heavily pressed to expel the juices which are usually concentrated to a syrup in the industry.
The term citrus molasses as used herein will be construed to mean the expelled juices from citrus waste residue and not be limited only to the concentrated syrup product. In reference to a citrus waste residue, this may be obtained from various citrus fruits of commercial value, for example oranges, grapefruit, lemons and limes.
Citrus molasses typically will contain 9% to 15% soluble solids of which 60% to 70% are sugars. This corresponds to a Brix of between 6.degree. and 12.5.degree. and a moisture content of 90%. Total volatile compounds of 88.39% to 94.36% are typical. Citrus molasses contains sugars that are convertible to ethyl alcohol by yeast fermentation, but also contains non-fermentable sugars and substances that inhibit fermentation. Due to a lack of recognition of the presence of these inhibitors, or to an inability to remove them economically, the prior attempts to obtain ethyl alcohol from citrus wastes could not be economically justified.
The U.S. patent to Reich, U.S. Pat. No. 2,561,072 taught the partial concentration of citrus waste liquors followed by subjecting the partially concentrated liquors to alcoholic fermentation, evaporatively concentrating the fermented liquors, and separating alcohol from the vapors of the second concentration step. Citric acid was separated from the final concentrate, and the residue from the separation was able to be dried and utilized as an industrial product.
In one of the Reich embodiments, the process was carried out utilizing multiple-stage evaporation for preliminarily and finally concentrating the waste citrus liquors. However, we have found that the use of evaporator systems to volatilize the oils and concentrate the molases were not energy efficient, nor effective for satisfactory oil removal, and the capital costs were quite large. It was to overcome the shortcomings of these and other such systems that the present process was evolved.